We describe a system aimed at the in-situ 3D annotation of physical objects and environments by the use of augmented reality. The system integrates absolute positioning technology, in the form of GPS and UWB positioning, with real-time computer vision to create a virtual a??incident mapa??. The virtual map is constructed collaboratively by multiple operatives and a remote control centre. We demonstrate the system operating in a test environment that covers indoor and outdoor areas and explain how the technology may be used to assist forensic investigators as they collect and process evidence in a crime scene.